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md/raid5: finish support for DDF/raid6
DDF requires RAID6 calculations over different devices in a different order. For md/raid6, we calculate over just the data devices, starting immediately after the 'Q' block. For ddf/raid6 we calculate over all devices, using zeros in place of the P and Q blocks. This requires unfortunately complex loops... Signed-off-by: NeilBrown <neilb@suse.de>
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NeilBrown
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99c0fb5f92
commit
67cc2b8165
@ -136,6 +136,10 @@ static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
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/* Find first data disk in a raid6 stripe */
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static inline int raid6_d0(struct stripe_head *sh)
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{
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if (sh->ddf_layout)
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/* ddf always start from first device */
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return 0;
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/* md starts just after Q block */
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if (sh->qd_idx == sh->disks - 1)
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return 0;
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else
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@ -152,13 +156,15 @@ static inline int raid6_next_disk(int disk, int raid_disks)
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* 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
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* is raid_disks-1. This help does that mapping.
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*/
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static int raid6_idx_to_slot(int idx, struct stripe_head *sh, int *count)
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static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
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int *count, int syndrome_disks)
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{
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int slot;
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if (idx == sh->pd_idx)
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return sh->disks - 2;
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return syndrome_disks;
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if (idx == sh->qd_idx)
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return sh->disks - 1;
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return syndrome_disks + 1;
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slot = (*count)++;
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return slot;
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}
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@ -1267,6 +1273,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
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unsigned long chunk_number;
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unsigned int chunk_offset;
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int pd_idx, qd_idx;
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int ddf_layout = 0;
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sector_t new_sector;
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int sectors_per_chunk = conf->chunk_size >> 9;
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int raid_disks = previous ? conf->previous_raid_disks
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@ -1386,6 +1393,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
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qd_idx = 0;
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} else if (*dd_idx >= pd_idx)
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(*dd_idx) += 2; /* D D P Q D */
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ddf_layout = 1;
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break;
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case ALGORITHM_ROTATING_N_RESTART:
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@ -1400,6 +1408,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
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qd_idx = 0;
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} else if (*dd_idx >= pd_idx)
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(*dd_idx) += 2; /* D D P Q D */
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ddf_layout = 1;
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break;
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case ALGORITHM_ROTATING_N_CONTINUE:
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@ -1407,6 +1416,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
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pd_idx = raid_disks - 1 - (stripe % raid_disks);
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qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
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*dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
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ddf_layout = 1;
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break;
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case ALGORITHM_LEFT_ASYMMETRIC_6:
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@ -1454,6 +1464,7 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
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if (sh) {
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sh->pd_idx = pd_idx;
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sh->qd_idx = qd_idx;
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sh->ddf_layout = ddf_layout;
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}
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/*
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* Finally, compute the new sector number
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@ -1642,9 +1653,10 @@ static void compute_parity6(struct stripe_head *sh, int method)
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{
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raid5_conf_t *conf = sh->raid_conf;
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int i, pd_idx, qd_idx, d0_idx, disks = sh->disks, count;
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int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
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struct bio *chosen;
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/**** FIX THIS: This could be very bad if disks is close to 256 ****/
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void *ptrs[disks];
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void *ptrs[syndrome_disks+2];
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pd_idx = sh->pd_idx;
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qd_idx = sh->qd_idx;
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@ -1687,23 +1699,28 @@ static void compute_parity6(struct stripe_head *sh, int method)
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}
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/* Note that unlike RAID-5, the ordering of the disks matters greatly.*/
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/* FIX: Is this ordering of drives even remotely optimal? */
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for (i = 0; i < disks; i++)
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ptrs[i] = (void *)raid6_empty_zero_page;
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count = 0;
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i = d0_idx;
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do {
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int slot = raid6_idx_to_slot(i, sh, &count);
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int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
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ptrs[slot] = page_address(sh->dev[i].page);
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if (slot < sh->disks - 2 &&
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if (slot < syndrome_disks &&
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!test_bit(R5_UPTODATE, &sh->dev[i].flags)) {
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printk(KERN_ERR "block %d/%d not uptodate "
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"on parity calc\n", i, count);
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BUG();
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}
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i = raid6_next_disk(i, disks);
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} while (i != d0_idx);
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BUG_ON(count+2 != disks);
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BUG_ON(count != syndrome_disks);
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raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
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raid6_call.gen_syndrome(syndrome_disks+2, STRIPE_SIZE, ptrs);
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switch(method) {
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case RECONSTRUCT_WRITE:
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@ -1761,24 +1778,28 @@ static void compute_block_1(struct stripe_head *sh, int dd_idx, int nozero)
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static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
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{
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int i, count, disks = sh->disks;
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int syndrome_disks = sh->ddf_layout ? disks : disks-2;
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int d0_idx = raid6_d0(sh);
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int faila = -1, failb = -1;
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/**** FIX THIS: This could be very bad if disks is close to 256 ****/
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void *ptrs[disks];
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void *ptrs[syndrome_disks+2];
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for (i = 0; i < disks ; i++)
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ptrs[i] = (void *)raid6_empty_zero_page;
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count = 0;
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i = d0_idx;
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do {
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int slot;
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slot = raid6_idx_to_slot(i, sh, &count);
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int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
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ptrs[slot] = page_address(sh->dev[i].page);
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if (i == dd_idx1)
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faila = slot;
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if (i == dd_idx2)
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failb = slot;
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i = raid6_next_disk(i, disks);
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} while (i != d0_idx);
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BUG_ON(count+2 != disks);
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BUG_ON(count != syndrome_disks);
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BUG_ON(faila == failb);
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if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
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@ -1787,9 +1808,9 @@ static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
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(unsigned long long)sh->sector, dd_idx1, dd_idx2,
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faila, failb);
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if ( failb == disks-1 ) {
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if (failb == syndrome_disks+1) {
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/* Q disk is one of the missing disks */
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if ( faila == disks-2 ) {
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if (faila == syndrome_disks) {
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/* Missing P+Q, just recompute */
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compute_parity6(sh, UPDATE_PARITY);
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return;
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@ -1804,12 +1825,13 @@ static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
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}
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/* We're missing D+P or D+D; */
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if (failb == disks-2) {
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if (failb == syndrome_disks) {
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/* We're missing D+P. */
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raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
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raid6_datap_recov(syndrome_disks+2, STRIPE_SIZE, faila, ptrs);
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} else {
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/* We're missing D+D. */
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raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
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raid6_2data_recov(syndrome_disks+2, STRIPE_SIZE, faila, failb,
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ptrs);
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}
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/* Both the above update both missing blocks */
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@ -201,6 +201,7 @@ struct stripe_head {
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sector_t sector; /* sector of this row */
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short pd_idx; /* parity disk index */
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short qd_idx; /* 'Q' disk index for raid6 */
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short ddf_layout;/* use DDF ordering to calculate Q */
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unsigned long state; /* state flags */
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atomic_t count; /* nr of active thread/requests */
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spinlock_t lock;
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